Fiber Holder Research Articles

Ammonia detection in water using balloon-like fiber optic sensor coated with oxazine and PDMS

This paper presents the detection of ammonia in water using a balloon-like fiber optic sensor coated with Oxazine 170 perchlorate and polydimethylsiloxane (PDMS). The sensor was prepared by removing a middle portion of a plastic optical fiber cladding using acetone. The uncladded fiber optic sensor was then bent into a balloon-like shape using a 3D printed fiber holder to fix the diameter of the bent structure and a shrink tube to maintain the curvature of the balloon-like structure. A thin layer of Oxazine 170 perchlorate (sensing material) was then deposited on the fiber surface before it was dip coated with PDMS for the protection of the sensing material. Experimental results revealed that the sensor has linear relationship with ammonia concentration ranging from 0 mg/L to 15 mg/L. Moreover, the sensor managed to achieve the sensor sensitivity of 0.006 (mg/L)−1, linearity of 0.9154, resolution of 1.6667 mg/L, LOD of 2.9556 mg/L, average stability precision of 99.8 % and RSD of 0.0308 %.

Selective Sampling to and Desorption from Single Solid-Phase Microextraction Arrow Fiber for Replicative and Quantitative Analysis.

New analytical functionality is demonstrated with an enclosed interface that joins a solid phase microextraction (SPME) device, a direct analysis in real time (DART) probe, and a high-resolution mass spectrometer. With a single 20 mm long SPME Arrow, the interface is able to perform five discrete DART analyses on different areas of the same fiber in 1 min of practical operation time. Three-fiber replicates for 15 runs total produce 15% or better center of variance (CV) values for both volatile headspace sampling and direct immersion sampling of a solvated analyte. Chemometric analysis of rapidly acquired headspace data is able to distinguish volatile profiles. Selective desorption within the interface also confers the ability to selectively sample to discrete areas of a fiber, and three different headspace samples or five different liquid samples can be acquired and differentiated with one Arrow. A five-point standard addition curve is constructed to measure the concentration of the solvated analyte. Unmodified commercial components of the analysis system include the fiber itself, the Orbitrap and AccuTOF mass spectrometer platforms, and the conditioning gas chromatograph inlet. Machine diagrams for the SPME-DART interface and Arrow fiber holder are included.

Development of optical sensor system and hardware base frame for checking the light and radiation fields of a linear accelerator

This study aims to quantitatively evaluate the light and radiation fields of a linear accelerator by developing an optical sensor quality assurance (QA) system using a cadmium sulfide (CdS) photodetector cell and a hardware base frame manufactured in-house. The CdS photodetector cell used as the optical sensor has a size of 3.4 × 4.1 mm2, can measure up to 100 lux of light, and has a response time of approximately 20 to 30 ms. To check the alignment of the light field, it was manufactured with a CdS cell optical fiber holder, and the microcontroller board and control module were configured to scan the light field profile. Additionally, for accurate operation of the sensor, it was programmed using the integrated development environment (IDE) sketch. The alignment check of the radiation field was analyzed using the image data measured with electronic portal imaging device (EPID) using the manufactured hardware base frame. An analysis program written in MATLAB was used to evaluate the alignment of the radiation field. For symmetric fields measured using the optical sensor QA system, the full width at half maximum (FWHM) values of crossline (X) and inline (Y) profiles were 100.391 mm and 98.725 mm, respectively, for a field size of 100 × 100 mm2, and 199.093 mm and 198.886 mm, respectively, for a field size of 200 × 200 mm2. The X and Y FWHM values measured by the sensor system for the light fields were within 1 mm of the field size of the visual inspection. In addition, the FWHM value of the asymmetric radiation field measured using the fabricated frame and EPID was measured from the center bearing ball of the field to the bearing ball in each field of the four directions in the EPID image, and when the X1, X2, Y1, and Y2 jaws were opened by 50 mm, FWHM values were 50.120 mm, 50.240 mm, 48.860 mm, and 49.870 mm, respectively. The corresponding values were 99.520 mm, 99.570 mm, 99.010 mm, and 99.880 mm when the jaw fields were opened by 100 mm. The optical sensor system and hardware base frame developed in this study demonstrated the ability to evaluate both light and radiation fields more simply and quantitatively when compared to the conventional QA process. This QA system will provide medical physicists with more reliable QA results than the conventional QA method that uses graph paper and film.

A Contact-Sensitive Probe for Biomedical Optics.

Capacitive proximity sensing is widespread in our everyday life, but no sensor for biomedical optics takes advantage of this technology to monitor the probe attachment to the subject’s skin. In particular, when using optical monitoring devices, the capability to quantitatively measure the probe contact can significantly improve data quality and ensure the subject’s safety. We present a custom novel optical probe based on a flexible printed circuit board which integrates a capacitive contact sensor, 3D-printed optic fiber holders and an accelerometer sensor. The device can be effectively adopted during continuous monitoring optical measurements to detect contact quality, motion artifacts, probe detachment and ensure optimal signal quality.

Enhanced fiber mounting and etching technique for optimized optical power transmission at critical cladding thickness for fiber-sensing application

Optical fibers offer various applications to cater to industrial needs, from power and data transmission to environmental sensing. Different sensing mechanisms of optical fibers depend on modifications made to the fiber itself primarily in the cladding and core sections. Different types of optical fiber sensors may require thinning of the cladding to allow propagated light to interact closer to the environmental stimuli. Chemical etching is commonly used for the de-cladding of a fiber, and there are many ways to execute this method. A conventional method of chemical etching is typically used for cladding removal. This paper reports and discusses the effectiveness of enhanced techniques for improvement towards conventional chemical etching methods with the assistance of a makeshift fiber holder. The fiber holder allows the fiber to be oriented well, allowing for smoother etching and thus conserving its mechanical structure. Thickness reduction is seen to be more consistent when the enhanced technique is employed, and the fiber takes a longer time (∼45 min) to break. This allows etching of the cladding close to the core, which is more manageable for the user if very thin cladding is required. A fiber etched without any holder tends to break earlier (∼35 min) than expected with a rather wide error margin. The lower coefficient of determination, R 2 values (95%) of the thickness reduction from conventional etching shows irregular thickness along the fibers. Optical power also fluctuates between 30–35 dBm for the conventional method, while the mounted fiber technique maintains stable optical power at 50 dBm during etching. Therefore, it is concluded that proper fiber horizontal fiber orientation during etching has a significant effect on the fiber strength due to the smooth cladding removal around the corecore while minimizing any permanent power loss to or the occurrence of fluctuations in the fiber. This smooth and efficient etching technique allows the production of enhanced fiber sensors with minimal structural or power defects.

Fusion and Elongation Method Integrated with Vacuum System to Fabricate Single-Mode Fiber Couplers

. The single mode fiber coupler has been successfully fabricated in various power ratio based on fusion and elongation method. Two single mode fibers were joined by heating them under the torch flame injected by H2 Gas with the temperature range of 1200°C - 1500°C. Coupling mode theory was determined to simulate the power characteristics of the fiber coupler which is then combined with the experimental results. The measurement of power output characteristics shows that good agreement between power ratio characteristic of experimental and theoretical simulation was obtained when the elongation process runs with a pulling speed of 180 μm/s. However, good performance of fiber couplers interm of coupling loss with typical of 0.05 dB has been obtained by integrating a vacuum system as the fiber holders inside the slot of pulling stages. Experimental results found that the suitable pressure of vacuum system operating during heating process is 120 mbar.

Dynamics rate of fiber chemical etching: new partial removal of cladding technique for humidity sensing application

Sensor-based optical fibers require thinner cladding for enhanced interaction between the evanescence wave and the environment. Fiber Bragg grated fiber sensors relying on an axial strain require chemical etching to weaken the fiber allowing more sensitivity in terms of strain. Ease of sensor multiplexing can be achieved through etching the mid-section of the fiber which is rarely reported with a custom-made holder. This paper proposes a technique for etching at the middle section of a fiber with a custom fiber holder. Chemical etching of a single-mode silica fiber was done with 48% hydrofluoric acid (HF). Etching proceeds until the fiber was completely etched. The optical spectrum was recorded at an interval of 3 min. Microscope visuals indicated possible etching with the mount design until ∼10 μm at 45 min with the fiber intact compared to a longer etching time. A longer etching duration than 45 min results in the optical spectrum displaying a null spectrum, depicting core damage. Etching of the fiber follows a linear trend and the reaction rate was determined to be 1.699 μm min−1 experimentally. The proposed fiber holder and receptacle were capable of etching a fiber with minimal defects while maintaining the ease of fiber handling.

Fiber positioning in microlens-fiber coupled integral field unit

A generic fiber positioning strategy and a fabrication path are presented for microlens-fiber-coupled integral field units. It is assumed that microlens-produced micro-images are carried to the spectrograph input through step-index,multi-mode fiber, but our results apply to micro-pupil reimaging applications as well. Considered are the performance trades between the filling percentage of the fiber core with the micro-image versus throughput and observing efficiency.A merit function is defined as the product of the transmission efficiency and the etendue loss. For a hexagonal packing of spatial elements, the merit function has been found to be maximized to 94% of an ideal fiber IFU merit value (which has zero transmission loss and does not increase the etendue) with a microlens-fiber alignment (centering) tolerance of 1 um RMS. The maximum acceptable relative tilt between the fiber and the microlens face has been analyzed through optical modeling and found to be 0.3 degree RMS for input f-ratio slower than f/3.5 but it is much more relaxed for faster beams. Several options of fabricating fiber holders have been compared to identify cost-effective solutions that deliver the desired fiber positioning accuracy. Femto-second laser-drilling methods deliver holes arrayed on plates with a position and diameter accuracy of 1.5 um RMS, and with an aspect ratio of 1:10. A commercial vendor produces plates with thickness of 5 mm, but with similar (1 um RMS) positioning accuracy. Both of these techniques are found to be moderately expensive. A purely photo-lithographic technique performed at WCAM (a facility at the University of Wisconsin, Madison), in tandem with deep reactive ion etching, has been used to produce a repeatable recipe with 100% yield. Photo-lithography is more precise (0.5 um RMS) in terms of hole positioning and similar diameter accuracy (1 um RMS).

Mechanical rotation and bending sensing by chiral long-period grating based on an axis-offset rotating optical fiber

A chiral long-period fiber grating (CLPFG) was fabricated by rotating the standard single mode fiber that was fixed on two fiber holders with an axis-offset. We investigated the performance of CLPFGs by sensing the mechanical twist, bending, and liquid refractive index experimentally. A wide twist sensing range of ±720° and 26.7 nm wavelength tuning range were achieved. Compared with tapered long-period fiber grating, the bending sensitivity of CLPFG is 5 times higher. Considering the simple and flexible fabrication process and low cost, this CLPFG may offer a simple and alternative choice for sensing mechanical deformation in industrial applications.

Open partial horizontal laryngectomy using CO2 fiber laser.

The application of CO2 fiber laser technology to ENT surgery has led to new interesting scenarios, both in endoscopic and in open surgical approaches. The current video shows three examples of open partial horizontal laryngectomies (OPHLs) performed using CO2 fiber laser for resection procedures. CO2 fiber laser helped the surgeon in improving the accuracy of resection and the quality of surgical margins on specimen. The low thermal damage on tissues resulted in minor postoperative edema and a fast recovery of laryngeal function. In our experience, the application of CO2 fiber laser showed some very useful features for performing OPHLs: a high cutting precision with very low tissue damage, the possibility of delivering energy without touching the organ, a modulable power for the various surgical steps, a very good maneuverability of the fine fiber holder during the procedure allowing the surgeon to "draw" the resection with a great accuracy.

A chiral long-period grating fabrication method based on axis-offset rotating optical fiber

We propose a method to fabricate chiral long-period grating (CLPG) by rotating the standard single mode fiber which is fixed on two fiber holders but with an axis-offset. We show that, compared with traditional fabrication methods, this axis-offset method is capable of obtaining identical resonance wavelengths of the CLPGs for the same grating period. We investigate the performance of CLPGs by detecting the interference between the light emerging from CLPGs and a reference light. The achieved forklike and spiral interference patterns both confirm the generation of ± 1-order optical vortex through CLPG. Experimental results indicate that high-quality CLPGs can be easily and repeatedly fabricated by this method.

Resistant/susceptible classification of respiratory tract pathogenic bacteria based on volatile organic compounds profiling

Resistance to antibiotics is an emerging and growing threat. To address this threat, attempts are being made by researchers to identify the Volatile Organic Compounds (VOCs) of bacteria. It is believed that unique combinations could be found among the VOCs produced by each microorganism. The current study aimed to identify and compare the VOCs of antibiotic-resistant and standard strains of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae. A polymer of divinylbenzene /carboxen /polydimethylsiloxane was applied for absorption of volatile compounds in headspace bacterial samples in form of a solid phase micro-extraction fiber holder. Gas chromatography-mass spectrometry technique was used for identification of volatile compounds. The analysis of the VOCs indicated that some VOCs appeared only in standard strains while others were common only among resistant strains. Exclusive VOCs to a specific strain were also detected. This study demonstrated that resistant strains of bacteria produced VOCs that were different from those of the standard strains. In addition, VOCs released by bacteria after passing the logarithmic growth phase showed no significant differences. The identification of VOCs can be a precise way to differentiate bacterial species, also it can be said that the VOCs produced by different pathogenic microorganisms can be the suitable biomarkers for their detection.

Spatially extended versus frontal cerebral near-infrared spectroscopy during cardiac surgery: a case series identifying potential advantages.

Stroke due to hypoperfusion or emboli is a devastating adverse event of cardiac surgery, but early detection and treatment could protect patients from an unfavorable postoperative course. Hypoperfusion and emboli can be detected with transcranial Doppler of the middle cerebral artery (MCA). The measured blood flow velocity correlates with cerebral oxygenation determined clinically by near-infrared spectroscopy (NIRS) of the frontal cortex. We tested the potential advantage of a spatially extended NIRS in detecting critical events in three cardiac surgery patients with a whole-head fiber holder of the FOIRE-3000 continuous-wave NIRS system. Principle components analysis was performed to differentiate between global and localized hypoperfusion or ischemic territories of the middle and anterior cerebral arteries. In one patient, we detected a critical hypoperfusion of the right MCA, which was not apparent in the frontal channels but was accompanied by intra- and postoperative neurological correlates of ischemia. We conclude that spatially extended NIRS of temporal and parietal vascular territories could improve the detection of critically low cerebral perfusion. Even in severe hemispheric stroke, NIRS of the frontal lobe may remain normal because the anterior cerebral artery can be supplied by the contralateral side directly or via the anterior communicating artery.

Fiber refractive index sensor based on dual polarized Mach–Zehnder interference caused by a single-mode fiber loop

A novel refractive index (RI) sensor head is proposed and experimentally demonstrated in this paper. The proposed sensor head is composed of a segment of bared single-mode fiber and a fiber holder that is fabricated by a 3D printer. The mechanism of the sensor head is based on dual polarized Mach-Zehnder interference. According to the aforementioned mechanism, we derived that the RI responses of the resonance dips possess an exponential functional manner when the E field is along the fast or slow axes. In addition, based on the finite element method, we found that the resonance dips wavelength responses are more sensitive when the input E field is along the fast axis. A confirmation experiment was performed, and the results confirmed our hypothesis. The maximum arithmetic mean value of RI response is about 657.895 nm/RIU for the proposed sensor head when the ambient RI changes from 1.3350 to 1.4110. Moreover, in the case of the proposed liquid RI sensor head, aligning the E field along the fast axis is the potentially needed condition for polarization.

Optical Fiber Lightening for Fluorescence Signal Detection with Thermal Stability in Dentistry

Dental caries diagnosis system has been made with a fiber lighting, camera module and band pass filter. By simply aligning a 405 nm LED (Light Emitting diode) chips directly connected polymer fibers, a compact lighting for dental fluorescence imaging could be implemented. Special designed fiber holder with proper hole diameter was fabricated to directly connect polymer fibers with 1 mm fiber diameter and increased coupling efficiency between fibers and LEDs. Fibers connected to fiber holder were polished by polishing machine to reduce insertion loss of the fiber. Experimentally, an optical insertion loss of the fiber bundle of up to 0.8 dB was achieved. Further, LED array module was packaged with equally spaced LED chips with fiber holder on metal. Fiber lightening was fabricated with directly coupled between LED array module and fiber bundle by UV epoxy without focusing lens in order to lower the lightening temperature of intraoral camera in the human mouth. The measured temperature of fabricated fiber lightening was about 25 degree celcius. To achieve a fluorescence image and dental caries diagnosis, the proper optical filter, camera module, 405 nm fiber bundle lighting and software were investigated. The performance of the fluorescence intraoral camera with fiber lightening is confirmed by fluorescence image of human tooth.

Development and operation of a high-throughput accurate-wavelength lens-based spectrometer.

A high-throughput spectrometer for the 400-820 nm wavelength range has been developed for charge exchange recombination spectroscopy or general spectroscopy. A large 2160 mm(-1) grating is matched with fast f/1.8 200 mm lenses, which provide stigmatic imaging. A precision optical encoder measures the grating angle with an accuracy ≤0.075 arc sec. A high quantum efficiency low-etaloning CCD detector allows operation at longer wavelengths. A patch panel allows input fibers to interface with interchangeable fiber holders that attach to a kinematic mount at the entrance slit. Computer-controlled hardware allows automated control of wavelength, timing, f-number, automated data collection, and wavelength calibration.

TU-F-12A-06: BEST IN PHYSICS (IMAGING) - A Novel Catheter-Based Radionuclide Imaging System to Characterize Atherosclerotic Plaque

Purpose: Atherosclerosis underlies coronary artery diseases, the leading cause of death in the United States and worldwide. In this study, we developed a novel catheter-based radionuclide imaging (CRI) system to image 18F-fluorodeoxyglucose (18F-FDG), a radionuclide, a marker of vascular inflammation, in murine carotid arteries and characterized the system for spatial resolution from multiple scintillating materials. Methods: The catheter system includes 35 mm and 8 mm fixed focal length lenses, which are subsequently connected to a CMOS camera and fiber holder. The distal ferrule of an image bundle is terminated with a wide-angle lens. The novelty of this system is a scintillating balloon with a crystal tip in the front of the wide angle lens to image light from the decay of 18F-FDG emission signal. The scintillating balloon is fabricated from 1mL of silicone RTV catalyst mixed with 1 mL base and 50 mg/mL calcium fluoride doped with Europium (CaF2:Eu). To identify the optimal scintillating materials with respect to resolution, we calculated modulation transfer function (MTF) of Yttrium Aluminum Garnet doped with Cerium (YAG:Ce), anthracene, and CaF2:Eu phosphors using a thin line optical phantom (Fig. 1a-1b). Macrophage-rich FVB murine atherosclerotic carotid plaque model (n = 4) was used in ex vivo experiments. Confirmatory imaging was also performed by an external optical imaging system (IVIS-200). Results: Analysis of the different phosphors (Fig 1b) showed that CaF2:Eu enabled the best resolution of 1.2μm. The CRI system visualized 18F-FDG in atherosclerotic plaques (Fig. 1d). The ligated left carotid (LR) artery exhibited 4× higher 18F-FDG signal intensity compared to the non-ligated right carotid (negative control) artery (1.65×10^2 ±4.07×10^1 vs. 4.44×10^1±2.17×10^0, A.U., p = 0.005) and confirmed with IVIS-200 (Fig. 1d). Conclusion: This CRI system enables high-resolution and sensitive detection of 18F-FDG uptake by murine atherosclerotic plaques.

Abstract 313: A Novel Catheter-Based Radionuclide Imaging System to Characterize Atherosclerotic Plaque

Objectives: Atherosclerosis underlies coronary artery diseases—the leading cause of death in the United States and worldwide. In this study, we developed a novel catheter-based radionuclide imaging (CRI) system to image 18 F-fluorodeoxyglucose ( 18 F-FDG), a radionuclide, a marker of vascular inflammation, in murine carotid arteries and characterized the system for spatial resolution from multiple scintillating materials. Methods: The catheter system includes 35 mm and 8 mm fixed focal length lenses, which are subsequently connected to a CMOS camera and fiber holder. The distal ferrule of an image bundle is terminated with a wide-angle lens. The novelty of this system is a scintillating balloon with a crystal tip in the front of the wide angle lens to image light from the decay of 18 F-FDG emission signal. The scintillating balloon is fabricated from 1mL of silicone RTV catalyst mixed with 1 mL base and 50 mg/mL calcium fluoride doped with Europium (CaF 2 :Eu). To identify the optimal scintillating materials with respect to resolution, we calculated modulation transfer function (MTF) of Yttrium Aluminum Garnet doped with Cerium (YAG:Ce), anthracene, and CaF 2 :Eu phosphors using a thin line optical phantom (Fig. 1a-1b). Macrophage-rich FVB murine atherosclerotic carotid plaque model (n = 4) was used in ex vivo experiments. Confirmatory imaging was also performed by an external optical imaging system (IVIS-200). Results: Analysis of the different phosphors (Fig 1b) showed that CaF 2 :Eu enabled the best resolution of 1.2μm. The CRI system visualized 18 F-FDG in atherosclerotic plaques (Fig. 1d). The ligated left carotid (LR) artery exhibited 4.9х higher 18 F-FDG signal intensity compared to the non-ligated right carotid (negative control) artery (2.6х10 4 ±1.4х10 3 vs. 5.4х10 3 ±1.3х10 3 , A.U., p = 0.008) and confirmed with IVIS-200 (Fig. 1d). Conclusions: This CRI system enables high-resolution and sensitive detection of 18 F-FDG uptake by murine atherosclerotic plaques.

Theoretical shape analysis of tapered fibers using a movable large-zone furnace

To estimate the shape of tapered fibers using tapering machines with movable large-zone furnaces, a new calculation method is proposed based on the discrete deducing method and the principle of the volume conservation of the fiber materials. This method can estimate the tapering results, i.e., the shape of the tapered fibers, based on arbitrary moving parameters of the large-zone furnace and the fiber holders. The theoretical estimated results agree with the experimental measuring shape of the tapered fibers quite well.

Design of a fiber-collimated array for beam combining

In this paper, we present the design of a very precise collimated fiber array that meets requirements for beam combining. Calculations permit to determine the tolerances toward key parameters and specify the components to manufacture. Thus, the collimated fiber array is composed of a high quality commercial microlens array and an especially dedicated fiber holder that we design and realize experimentally. Manufacture techniques for both the microlens and the holder are chosen to be collective and then compatible with a high number of fibers. With the collimated fiber array hence obtained, the individual beam quality was measured to be λ/10 and the pointing accuracy is under 0.6 mrad.